Eclipse to accompany Tuesday's solstice

But chance of a white Christmas slim, weather experts say

Published 9:36 pm, Sunday, December 19, 2010

Tuesday's winter solstice ---- the shortest day of the year ---- will be special for another reason, there will be an eclipse of the moon in the early morning hours, roughly between 2:41 and 3:53 a.m.

This is when the full moon will slip into the earth's shadow, and for a lunar eclipse to occur on the same date as the solstice is unusual indeed.

According to NASA, it's only happened once in the last 2,000 years, in 1638. Despite this, there are more than a few people alive today who will live to see the next winter solstice eclipse, which will occur in 2094, NASA says.

Whether you decide to stay up late or get up early to watch the event is your call. Viewers will likely be treated to a dim, copper-colored moon.

This is because during a lunar eclipse, the moon is illuminated only by the light passing through the earth's atmosphere. The more dust and pollution present in the global atmosphere, the redder the moon will appear at totality. It's impossible to predict how the eclipsed moon will appear, experts say.

Viewed from the moon, the sun-blocking earth would appear as an orange ring as every sunset and every sunrise would be seen all at once. It's the light from this orange ring that will make the moon visible from our planet while it's in the earth's shadow.

It's also possible that the moon will disappear almost completely from view if atmospheric conditions are especially clear on earth. Total lunar eclipses are rated on what's called the Danjon scale, with L-0 being a very dark, almost invisible moon and L-4 being a very bright, coppery moon.

The moon will appear darkest at 3:17 a.m., when the moon will be in the deepest shadow.

This will also be the only total lunar eclipse of 2010; there was a partial lunar eclipse on June 26, which was only visible from Pacific regions.

Technically, the eclipse will occur during the waning hours of the autumn season. The winter solstice, the moment at which the earth's axis is tilted farthest from the sun, will occur on Tuesday at 6:38 p.m. It's at this moment that winter in the northern hemisphere officially begins.

Tuesday will also be the day of the year with the shortest day and the longest night. In southwestern Connecticut, sunrise on Tuesday will occur at 7:15 a.m. and sunset will occur at 4:27 p.m.; there will be only 9 hours and 12 minutes of sunlight.

Cultures throughout the world, both past and present, mark or marked the shortest day with festivities of all descriptions. For example, historians say that the celebration of Christmas has its roots in one or more of these ancient winter solstice events, such as Rome's Saturnalia or the Yule celebrations of pagan Scandinavia.

As to whether southwestern Connecticut will see a white Christmas, meteorologists say that the chance of that happening is slim -- at least according to the strict definition that weather experts have of a "white Christmas."

"Officially, to have a white Christmas, you have to have an inch of snow on the ground on Christmas day," said meteorologist Jess Parker of weatherundergound.com. That's not likely to happen, she said, although there could be snow falling by Saturday evening.

"There's a weather system coming in from the Midwest," she said. "This will head toward the Mid-Atlantic states before it lifts toward the Northeast."

Parker said that the greatest chance for snowfall will be on Saturday evening.

"It'll be about a 30 percent chance of snow on Christmas day, and that probability will increase on Sunday," she said. "We'll know more by late Monday, because the computer models that we're using are diverging quite a bit. There's a system in the Canadian Maritimes that might block that snow."

As for the probability of a white Christmas, the National Climatic Data Center places that chance at 11 percent to 25 percent along the shore of southwestern Connecticut. The probability increases dramatically just a few miles to the north; in northern Litchfield County, there's a 61 percent to 75 percent chance of seeing snow on the ground Christmas morning.

But even though there won't be much in the way of snow Christmas morning, Parker said that it will be a good week for travel in the Northeast. "There's really not much going on this week," she said.